code: def standarddev(x):
      return math.sqrt(average(variance(x)))
  
file_path: backtrader/samples/sratio/sratio.py
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import argparse
  import itertools
  import math
  import operator
  import sys
label_desc: Use image node_id 3 for calling a global function with example usage: standarddev(x) and returns: math